Approximately 10% of the population become hypersensitized (allergic) upon exposure to antigens from a variety of environmental sources. Those antigens that induce immediate and/or delayed types of hypersensitivity are known as allergens (King, T. P., (1976) Adv. Immunol., 23:77-105). These include products of grasses, trees, weeds, animal dander, insects, food, drugs, and chemicals. Genetic predisposition of an individual is believed to play a role in the development of immediate allergic responses (Young, R. P. et al., (1990) Clin. Sci., 79:19) such as atopy and anaphylaxis whose symptoms include hay fever, asthma, and hives.
The antibodies involved in atopic allergy belong primarily to the IgE class of immunoglobins. IgE binds to basophils, mast cells and dendritic cells via a specific, high-affinity receptor Fcxcex5RI (Kinet, J. P., (1990) Curr. Opin. Immunol., 2:499-505). Upon combination of an allergen acting as a ligand with its cognate receptor IgE, FceRI bound to the IgE may be cross-linked on the cell surface, resulting in physiological manifestations of the IgExe2x80x94allergen interaction. These physiological effects include the release of, among other substances, histamine, serotonin, heparin, chemotactic factor(s) for eosinophilic leukocytes and/or leukotrienes C4, D4, and E4, which cause prolonged constriction of bronchial smooth muscle cells (Hood, L. E. et al., Immunology (2nd ed.), The Benjamin/Cumming Publishing Co., Inc. (1984)). Hence, the ultimate consequence of the interaction of an allergen with IgE is allergic symptoms triggered by the release of the aforementioned mediators. Such symptoms may be systemic or local in nature, depending on the route of entry of the antigen and the pattern of deposition of IgE on mast cells or basophils. Local manifestations generally occur on epithelial surfaces at the site of entry of the allergen. Systemic effects can induce anaphylaxis (anaphylactic shock) which results from IgE-basophil response to circulating (intravascular) antigen.
Studies with purified allergens have shown that about 80% of patients allergic to the mite Dermatophagoides pteronyssinus produce IgE reactive to Der p I and Der p II (Chapman M. D. et al., J. Immunol. (1980) 125:587-92; Lind P., J. Allergy Clin. Immunol. (1985) 76:753-61; Van derZee J. S. et al., J. Allergy Clin. Immunol. (1988) 81:884-95). For about half of the patients, these specificities constitute 50% of the IgE antimite antibody. The allergen Der p III, recently identified as trypsin, (Stewart G. A. et al., Immunology (1992) 75:29-35) reacts with a similar or higher frequency (Stewart G. A. et al., supra; Ford S. A. et al., Clin. Exp. Allergy (1989) 20:27-31). However, in the only quantitative study performed to date, the investigators reported the level of IgE binding to be considerably less than Der p I. Electrophoretic techniques (Ford S. A. et al, supra; Bengtsson A. et al., Int. Arch. Allergy Appl. Immunol. (1986) 80:383-90; Lind P. et al., Scand. J. Immunol. (1983) 17:263-73; Tovey E. R. et al, J. Allergy Clin. Immunol. (1987) 79:93-102) have shown that most sera recognize other allergens. For example, in the study of Ford et al (supra) Western blotting showed 8 sera reacting with 1-2 bands, 6 with 3-6 and 3 with a greater number including one with at least 13. In another study, Baldo et al. (Adv. Bioscience (1989) 4:13-31) report the finding of components at Mr 30, 26, 25K reacting with 50% of sera. To determine the importance of particular specificities in the allergic reactions, purified allergens would be required for quantitative IgE binding tests and to examine the frequency and lymphokine profile for T cell reactivity.
Treatment of patients with sensitivity to house dust mites by administration of increasing doses of house dust extracts has the drawbacks of potential anaphylaxis during treatment and the possible necessity of continuing therapy over a period of several years to build up sufficient tolerance that results in significant diminution of clinical symptoms. A therapeutic composition and method of therapy which avoids these problems would be beneficial.
This invention provides isolated nucleic acids encoding peptides having at least one biological activity of Der p VII or Der f VII, protein allergens of the species Dermatophagoides pteronyssinus and Dermatophagoides farinae. Preferred nucleic acids are cDNAs having a nucleotide sequence shown in FIGS. 3A and 3B (SEQ ID NO: 1) (Der p VII) and FIGS. 6A and 6B (SEQ ID NO: 6) (Der f VII). The invention also pertains to peptides encoded by all or a portion of such cDNAs (SEQ ID NO: 1 and SEQ ID NO: 6) and having at least one biological activity of Der p VII or Der f VII. Also contemplated are isolated nucleic acids which hybridize under high stringency conditions (e.g., equivalent to 20-27xc2x0 C. below Tm and 1M NaCl) to a nucleic acid having a nucleotide sequence shown in FIGS. 3A and 3B (SEQ ID NO: 1) or FIGS. 6A and 6B (SEQ ID NO: 6) or which encodes a peptide comprising all or a portion of an amino acid sequence of FIGS. 3A and 3B (SEQ ID NO: 2)(Der p VII) or FIGS. 6A and 6B (SEQ ID NO: 7)(Der f VII). Nucleic acids which encode peptides having an activity of Der p VII or Der f VII and having at least 50% homology with a sequence shown in FIGS. 3A and 3B (SEQ ID NO: 2)(Der p VII) or FIGS. 6A and 6B (SEQ ID NO: 7)(Der f VII) are also featured. Peptides having a Der p VII or Der f VII activity produced by recombinant expression of a nucleic acid of the invention, and peptides having a Der p VII or Der f VII activity prepared by chemical synthesis are also featured by this invention. Preferred peptides have the ability to induce a T cell response, which may include T cell stimulation (measured by, for example, T cell proliferation or cytokine secretion) or T cell nonresponsiveness (i.e., contact with the peptide or a complex of the peptide with an MHC molecule of an antigen presenting cell induces the T cell to become unresponsive to stimulatory signals or incapable of proliferation). Other preferred peptides, either apart from or in addition to the ability to induce a T cell response, have the ability to bind the dust mite specific IgE of dust mite-allergic subjects. Such peptides are useful in diagnosing sensitivity to dust mite in a subject. Still other peptides, either apart from or in addition to the ability to induce a T cell response, have a significantly reduced ability to bind dust mite-allergic IgE. Such peptides are particularly useful as therapeutic agents.
Other preferred peptides comprise an amino acid sequence shown in FIGS. 3A and 3B (SEQ ID NO: 2) (Der p VII) or FIGS. 6A and 6B (SEQ ID NO: 7) (Der f VII). In one embodiment, peptides having a Der p VII or Der f VII activity and comprising a portion of the amino acid sequence of FIGS. 3A and 3B (SEQ ID NO: 2) or FIGS. 6A and 6B (SEQ ID NO: 7) are featured. Such peptides are at least about 8-30 amino acids in length, preferably about 10-20 amino acids in length, and most preferably about 10-16 amino acids in length.
Another aspect of the invention features antibodies specifically reactive with a peptide having a Der p VII or Der f VII activity. A peptide having an activity of Der p VII or Der f VII can be used in compositions suitable for pharmaceutical administration. Such compositions can be used in a manner similar to dust mite extracts to treat or prevent allergic reactions to a dust mite allergen in a subject. Nucleic acids of the invention and peptides having an activity of Der p VII or Der f VII can also be used for diagnosing sensitivity in a subject to a dust mite allergen.